A radar system is known, for example, from International Patent Publication No. WO 97/02496. The radar system according to this document has three combined transmission/reception elements which, in conjunction with a shared antenna lens, form three transmission and reception lobes. Reflected radar signals which are received via these three reception lobes are first processed in three parallel signal paths. On the basis of an amplitude analysis, an angular position of all detected objects can be calculated.
For future, expanded applications of such radar systems, for example in traffic jams or in city traffic, there is now a requirement that the observable angular region be widened, especially in the close-in range of the radar system.
Difficulties arise in this connection in that the received radar signals are generally very weak, and accordingly, in order to eliminate unnecessary additional damping, must be prepared and processed as immediately as possible after they are received. In this context, it is advantageous to provide first amplifier stages and/or mixer stages in each reception path so as thereby to eliminate, to the extent possible, signal-damping high-frequency switchers or multiplexers. The result of this, however, is that when the observable angular region is enlarged by expanding the transmission/reception concept known from the aforementioned document--i.e. by adding further transmission/reception elements--the circuit complexity on the reception side, and therefore a substantial cost factor, increases sharply. A simple widening of the individual transmission/reception lobes used hitherto would, on the other hand, degrade the angular resolution hitherto obtained.
An anti-collision motor vehicle radar which possesses two transmission antennas and only one reception antenna is known from U.S. Pat. No. 4,308,536. The two transmission antennas possess antenna lobes which each occupy an angle of 3 degrees with respect to the longitudinal axis of the motor vehicle. The width of each lobe is 10 degrees. The principal beam direction of the reception antenna is aligned along the longitudinal axis of the motor vehicle. The output pulses of a transmitter are switched over alternately, by means of a switch, to the two transmission antennas. The observable angular region in this case is 16 degrees. This is too small in terms of the desired future applications. With this principle, known generally as "sequential lobing," a widening of the observable angular region has a disadvantageous effect on the accuracy of the angular measurement.
A radar system of the species which possesses four individually activatable transmission elements and six simultaneously utilized reception elements is known from European Patent No. EP 568 427 A1. In this system as well, the observable angular region is 16 degrees, which, as already mentioned, is too small for future applications